Alleviating the $H_0$ tension through new interacting dark energy model in light of DESI DR2

TL;DR

The paper tackles the persistent $H_0$ tension by testing two interacting dark energy scenarios, $\widetilde{\Lambda}$CDM and $e\widetilde{\Lambda}$CDM, against DESI DR2 BAO, Planck+ACT CMB, SN compilations, and SH0ES data. It introduces scale-dependent $G(z)$ and $\Lambda(z)$ through $G(z)/G_0=(1+z)^{-\delta_G}$ and $\Lambda(z)/\Lambda_0=(1+z)^{\delta_\Lambda}$, with a low-redshift relation $\delta_\Lambda \approx 0.47\,\delta_G$, and distinguishes between a one-parameter (tilde-$\Lambda$CDM) and a two-parameter ($e\widetilde{\Lambda}$CDM) extension. Key results show that $e\widetilde{\Lambda}$CDM can raise $H_0$ when SH0ES is included (e.g., $H_0=71.90\pm1.00$ km/s/Mpc with $\delta_{\Lambda}=-0.410^{+0.140}_{-0.120}$), reducing the tension to about $0.8\sigma$, while still accommodating DESI data; without SH0ES, $H_0=70.00\pm1.50$ km/s/Mpc (1.7$\sigma$). In contrast, DESI data mildly prefer a $w_0w_a$CDM extension, which worsens the tension to about $4.2\sigma$. Overall, the interacting model, particularly $e\widetilde{\Lambda}$CDM, provides a significant improvement over $\Lambda$CDM in reconciling local and early-Universe measurements, highlighting a promising direction for beyond-$\Lambda$CDM cosmology.

Abstract

The $H_0$ tension has become one of the most significant challenges in modern cosmology. The recent DESI DR2 data has shown a significant preference for dynamical dark energy, yet this has further exacerbated the $H_0$ tension. In this work, we explore the potential of new interacting dark energy models ($\widetildeΛ$CDM and $e\widetildeΛ$CDM) to alleviate the $H_0$ tension. We perform observational constraints using the latest baryon acoustic oscillation data from DESI DR2, cosmic microwave background (CMB) data from Planck and Atacama Cosmology Telescop, and type Ia supernova data from DESY5 and PantheonPlus, as well as the SH0ES data. From our analysis, we observe the dynamical scale parameter of the cosmological constant, $δ_Λ = -0.410^{+0.140}_{-0.120}$, in the $e\widetildeΛ$CDM model using the CMB+DESI+SH0ES data, which deviates from $Λ$CDM at the $3.2σ$ level. Due to the anti-correlation between $δ_Λ$ and $H_0$, a negative $δ_Λ$ results in a higher inferred $H_0$. Consequently, we obtain $H_0 = 71.90 \pm 1.00~\mathrm{km\,s^{-1}\,Mpc^{-1}}$, reducing the $H_0$ tension to $0.8σ$. Even without SH0ES, the CMB+DESI data alone still alleviate the $H_0$ tension to $1.7σ$. Overall, the $e\widetildeΛ$CDM model not only deviates from the $Λ$CDM model but also demonstrates a significant capability to alleviate the $H_0$ tension.

Figures (4)

• Figure 1: Constraints on the cosmological parameters from the combination of CMB, BAO, and SN data. Left panel: Constraints on the cosmological parameters obtained using the CMB+DESI, CMB+DESI+DESY5, and CMB+DESI+PantheonPlus data in the $\widetilde{\Lambda}$CDM model. Right panel: Constraints on the cosmological parameters obtained using the CMB+DESI, CMB+DESI+DESY5, and CMB+DESI+PantheonPlus data in the $e\widetilde{\Lambda}$CDM model.
• Figure 2: Constraints on the cosmological parameters from the combination of CMB, BAO, SN, and SH0ES data. Left panel: Constraints on the cosmological parameters obtained using the CMB+DESI+SH0ES, CMB+DESI+DESY5+SH0ES, and CMB+DESI+PantheonPlus+SH0ES data in the $\widetilde{\Lambda}$CDM model. Right panel: Constraints on the cosmological parameters obtained using the CMB+DESI+SH0ES, CMB+DESI+DESY5+SH0ES, and CMB+DESI+PantheonPlus+SH0ES data in the $e\widetilde{\Lambda}$CDM model.
• Figure 3: The $1\sigma$ error bar plots of $H_{0}$ in various cosmological models from the CMB+DESI, CMB+DESI+DESY5, CMB+DESI+PantheonPlus, CMB+DESI+SH0ES, CMB+DESI+DESY5+SH0ES, and CMB+DESI+PantheonPlus+SH0ES data. The circular markers represent results without including the SH0ES prior, while the square markers denote the constraints obtained when the SH0ES data are included.
• Figure 4: Best-fit predictions for distance-redshift relations for the $\Lambda$CDM, $\widetilde{\Lambda}$CDM, and $e\widetilde{\Lambda}$CDM models using CMB and DESI data. Upper panel: Best-fit predictions for distance-redshift relations for $\Lambda$CDM (solid line), $\widetilde{\Lambda}$CDM (dotted-dashed line), and $e\widetilde{\Lambda}$CDM (dashed line) obtained from the analysis of CMB+DESI data. The predictions encompass the three distinct types of distances probed by DESI BAO measurements, including $D_{\mathrm{H}}$ (left), $D_{\mathrm{M}}$ (middle), and $D_{\mathrm{V}}$ (right). The error bars represent $1\sigma$ uncertainties. Lower panel: Difference between the model prediction and data point for each BAO measurement, normalized by the observational uncertainties. The predictions for $\Lambda$CDM, $\widetilde{\Lambda}$CDM, and $e\widetilde{\Lambda}$CDM are shown by filled, cross-shaped markers, and plus signs, respectively.